i am curious,

4.126 bore x 3.0 stroke ( large journal)

what cubic inch would it make.

who sells pistons for this application.

what are pros vs cons.

how much h.p. and torque more over a exact built 302

thanks

320 ci.You could use 6.125" rods and 400 pistons for a 3.75 stroke and 5.7" rods most have a compression height of 1.420 to 1.430.You would have to use main bearing spacers.A large journal 3" crank is 2.46 a 400 is 2.65.Don't see a huge torque increase over a 302 IMO.I don't see where it would be worth doing.Most early 4" bore blocks will go .060 over you are only getting another .065 with the 400 block.

Bore = power. Basically with the short stroke you will just move your powerband way out making the same peak hp but with lower torque. So you will be spinnin significantly higher rpms. If thats what you want it would be worth it the thing would rev like crazy and make a little more power than 350 block

I wouldnt use less then a 3.25" crank in any standard deck smallblock.In order to get a good shortblock combo the rods need to be too long.You wont get any real RPM advantage since regardless of if you use real long rods or real tall pistons,the entire assembly will be too heavy.Comp eliminator guys run this combo but they use special chevy blocks that are shorter then a small block Ford and that lets then run shorter connecting rods.Hope this helps.

???? I completely missunderstand your logic. Correct me if I am wrong but the 302 block is the same block as a 327 which was the same bore as a 350. That being said. The 302 was built from a 283 crank to make the displacement requirements for the racing class in the day.

I know a guy who blueprinted his 302 z motor and was spinning 13k. Stroke = rpms because of the velocity of the intake air charge to make the peak power. Not entirely sure what the weight of the assembly has to do with anything considering how much lighter it will be than a diesel which has spun up to near 6k on a Duramax. Thats why things are balanced.

The thing will probably want to peak around 8-10 depending on how radical you go with the cam but the peak power will most likely not be below 6-7k while a 377 would be no less than 5-6k again depending on cam most likely higher.

I run my 383 to 7,200. Same cam with a 3.00 stroke could easily see 10 if not higher.

Eric KB forged pistons with a comp height of 1.261 and aftermarket long rods of 6.250 puts your piston -.014 in the hole. If you cut the deck .014 the piston will be right at the top of the deck. Downside is you have the spin the snot out of the motor to make it run. Upside is you can spin the snot out of the motor if you build it right and run 4 series gears. Why not spin it less and run a 350 crank for a 377 cid? It'll still rev to 6500 or 7K if you build it well, run a solid roller or FT solid cam. KB762 is the piston for that build, forged FT. Deck the block to 9.00, run a .038 gasket and with a 64cc head you have a 11:1 motor. 67 cc head = 10.6:1. Run a 6.00 rod with that piston. They are 2618 alloy which is more crack resistant than the 4032, but less resistant to scuffing. They also have anti-detonation radial grooves and a gas accumulator between the top and second rings.

???? I completely missunderstand your logic. Correct me if I am wrong but the 302 block is the same block as a 327 which was the same bore as a 350. That being said. The 302 was built from a 283 crank to make the displacement requirements for the racing class in the day.

I know a guy who blueprinted his 302 z motor and was spinning 13k. Stroke = rpms because of the velocity of the intake air charge to make the peak power. Not entirely sure what the weight of the assembly has to do with anything considering how much lighter it will be than a diesel which has spun up to near 6k on a Duramax. Thats why things are balanced.

The thing will probably want to peak around 8-10 depending on how radical you go with the cam but the peak power will most likely not be below 6-7k while a 377 would be no less than 5-6k again depending on cam most likely higher.

I run my 383 to 7,200. Same cam with a 3.00 stroke could easily see 10 if not higher.

13,000 RPM? You gotta be kidding! I find that hard to believe but I am no expert here. ;)

i am curious,

4.126 bore x 3.0 stroke ( large journal)

what cubic inch would it make.

who sells pistons for this application.

what are pros vs cons.

how much h.p. and torque more over a exact built 302

thanksThat could run hard, 475 HP can turn into 10.60s in a first gen camaro if the cars right. Example Jerry Ms D/S 67 Z28 camaro.

13,000 RPM? You gotta be kidding! I find that hard to believe but I am no expert here. ;)

Have a friend that turned his 302, 11000 but he had a mechanical roller cam roller rockers with rev kit and huge by large valve springs.

You're wanting to go to a 3.0" stroke crank in a 400 block?

You're going the wrong way. High revving engines are a ton of maintenance and tend to spread parts on the track. If you have a good 400 block, there's no reason at all not to build it with stock stroke. It'll still spin plenty high to get your butt puckered real tight and you'll have power thru the band rather than something that has to be wound up tight to make good power.

You don't have to rev the wee out of it-race or street?
pro's -it's what you want and differant
con's -it will be a bit soft on torque and won't be 350 cheap
HMM
195 afr's
cam in the 276 range
10 somthin to 1
close ratio 5 speed in a lighter car
sound's fun
400 somthin sound's extra fun though

13,000 RPM?
It might do it........ONCE!

I am raising the BS flag here.Anybody who tries to rev a 2 valve engine past about 10,500rpm isnt making much power,or has a prostock valvetrain.Even with the most current valvesprin technology,the mechanical limit of an engine with spring actuated valves is about 85 cycles per second.That translated into about 10,200rpm.Beyond that metal springs simply cant move fast enough regardless of pressure,height or anything else.With very low valve lifts you might be able to extend this to about 90 cycles P/S but part of the valve's action would be running off the closing ramp.Engines that spin faster then these numbers typically use pnumatic valve springs which as far as I know has never been run on anything other then really little formula 1 type 4 and 5 valve engines.

As far as building a 3" stroke shortblock,anything longer then about a 5.8" rod will cause induction problems and loose power.

Good luck.

13,000 rpm?
It might do it........once! lmao

You're wanting to go to a 3.0" stroke crank in a 400 block?

You're going the wrong way. High revving engines are a ton of maintenance and tend to spread parts on the track. If you have a good 400 block, there's no reason at all not to build it with stock stroke. It'll still spin plenty high to get your butt puckered real tight and you'll have power thru the band rather than something that has to be wound up tight to make good power.
I agree with Busted Knuckles, you are going the wrong way. Stroke=Torque!!! I raced a guy with a 377 (400 block w/350 crank) & I had a 383 (350 block w/400 crank) stroker both cars were the same. I could beat him every time in a drag race.

I agree with Busted Knuckles, you are going the wrong way. Stroke=Torque!!! I raced a guy with a 377 (400 block w/350 crank) & I had a 383 (350 block w/400 crank) stroker both cars were the same. I could beat him every time in a drag race.

But was everything else the same, weight of cars, transmission ratios and rearend ratios? If I had the choice between 377 and 383, it would be 377 every time. I like rpms.

One other option that is not quite as bad, would be to use a medium journal (2.45) 327 crank in a 400 block (2.65 mains) with spacer bearings.

3.25 stroke with 4.155 bore (0.030 over 400) = 352 cubic inches. I like this combination because it will rev and it's different.

What you'll end up with is a no torque street dog if a 3.00 stroke is put in a 400 block, the 302 is a no torque dog on the street. You'll have to rev the snot out of it and that requires very expensive valve train parts that will fail on a regular basis. I would do a 372 (4.125 bore) - 377 (4.155 bore) that is built with 350 crank (3.48 stroke) it will still have the torque of a 350 and the rpm range of a 327. Done right a 377 is a real screamer that runs like a beast and still has street manners. The 327 and the 377 have a very close bore stroke ratio which to some is the greatest SBC displacement. For a street car that you have to live with on a regular basis then build that block into a 406 with a 5.7 rod and revell in the torque, taller gears and fun highway miles are the pay off. Traco built the 372 for the Guldstrand GS80 Corvettes and let me tell you those things were a whole lot of fun, even with the L98 cylinder heads a Engle solid cam and the retrictive TPI intake they would pull down 400 lbs and 375 HP which pushed the 3200 pound Corvette to very low 12's on gaterbacks (spinning the tires quite hard). Sell the 3.00 crank to a Z/28 restorer.

Hope I don't sound insulting here, but I always seem to hear about these super short stroke projects from guys who don't have any real experience racing or building engines. It's because the guys that really want to go fast build big motors.

Cubic inches + air flow = power . . . not bore = power or stroke = power. Look at where the serious drag race guys spend their money. It isn't developing a bigger bore shorter stroke engine, its in the heads (airflow).

If you want to go fast and have a small block that revs, buy the baddest cylinder head you can afford and build a short block to match. Get the compression and cam right and you have a motor that accelerates fast -- if I want just a high RPM motor I'd get a model airplane engine.

I like RPM's too and have given serious thought to building a 302 based on a late model LT1 block using an L99 crank and rods with the stock LT1 pistons and keeping the injection. I have both engines gathering dust back in Kentucky. (LT1 and L99)

Cubic inches + air flow = power . . . not bore = power or stroke = power.



The reason I pulled my 327 and put a 400 in.

Hope I don't sound insulting here, but I always seem to hear about these super short stroke projects from guys who don't have any real experience racing or building engines. It's because the guys that really want to go fast build big motors.

Cubic inches + air flow = power . . . not bore = power or stroke = power. Look at where the serious drag race guys spend their money. It isn't developing a bigger bore shorter stroke engine, its in the heads (airflow).

If you want to go fast and have a small block that revs, buy the baddest cylinder head you can afford and build a short block to match. Get the compression and cam right and you have a motor that accelerates fast -- if I want just a high RPM motor I'd get a model airplane engine.

I appreciate the input from everyone, i just want to make clear, i was only asking a question..... not really considering the build ...just curiosity....

I restored and own a 1969 z/28, i do not want a 350, 377, 383, 400, etc..( but appreciate the input)


I also know the bigger the better, but for originalitys sake my car is staying a 302. I just want to squeeze some extra power out of the 302.

I also know its very expensive and it will cost me a lot more then building a larger displacement,

Personnaly a z/28 without a 302 is just a Camaro,

the short stroke will always make less power then the longer stroke engines, although for corner carving ( which a z/28 was designed for) the short stroke is very amusing ( much more then my other cars which have larger displacement engines).

And you can make a 302 run -- they sure did back in the late 60's.

Racing with courses that have turns besides at the end of the shut down are a whole new ball game. Traction and cornering become very important on ovals and road courses (just stating the obvious here) and massive TQ isn't necessarily what you want when drifting through a turn at 90 mph.

But was everything else the same, weight of cars, transmission ratios and rearend ratios? If I had the choice between 377 and 383, it would be 377 every time. I like rpms.

One other option that is not quite as bad, would be to use a medium journal (2.45) 327 crank in a 400 block (2.65 mains) with spacer bearings.

3.25 stroke with 4.155 bore (0.030 over 400) = 352 cubic inches. I like this combination because it will rev and it's different.
My car weighed more had stock chevy corvette aluminum heads, his are fully ported AFR's. I had a hyd. roller (less lift), his a mech. roller. Mine a 3.08 rear gear, his a 4.11 & a spool. He shifted at 9500 mine 6000 rpm. are you getting the picture. I ran 11.50's all day with a best of 11.39, his car has never seen an 11.50. TORQUE IS KING!!!:thumbsup:

Hope I don't sound insulting here, but I always seem to hear about these super short stroke projects from guys who don't have any real experience racing or building engines. It's because the guys that really want to go fast build big motors.

Cubic inches + air flow = power . . . not bore = power or stroke = power. Look at where the serious drag race guys spend their money. It isn't developing a bigger bore shorter stroke engine, its in the heads (airflow).

If you want to go fast and have a small block that revs, buy the baddest cylinder head you can afford and build a short block to match. Get the compression and cam right and you have a motor that accelerates fast -- if I want just a high RPM motor I'd get a model airplane engine.I agree, but Jerrys 10.60s from his HHRA stock 302 dont look that bad to me when you compare them to a 427 small block running 10.0s. The post was started by a guy who had a Z28, people who had these cars back in the day have nothing but great memories of these cars, back then there was no aftermarket anything, you put headers and an off road cam and 5.13 gears in that 12 bolt and you went huntin, yes todays different and you are right, but let me tell you, theres nothing like driving around town in a restored 67 Z28 with a 302 and a 4.56 gear, its a lot of fun! Id drive the Z before Id drive my 9sec drivers!

A lot of people seem to be stuck on the short stroke=RPM deal.Little engines make more power per cube which is good for a class race situation,but isnt the be all end all of performance.Lots of guys think the 400 or 383 is a low rpm piece,but nothing is further from the truth.A 3.75" crank in a bigblock is the stuff that 8500 rpm screamers are built from,yet in a smallblock,they are "torque monsters".A smallblock has lighter pistons and rods,and current piston technology has made it cheap to get longer rods on the 3.75" crank to keep the load off the walls.There are currently 23 degree smallblock heads that flow over 300CFM,so there is no reason not to build a 400 incher that spins to 7500 or better AND makes big power.Most guys would never want to drive a 7500 rpm 302 on the street since not only would it be tempermental,but would be short on low rpm power.A 400 incher would be just as tempermental,and wouldnt be all that strong down low,but it would still be 30% better at anything the 302 could do.If you want a screaming monster,you might as well build a big one.

My 68 Z28 has the 'born with' drive train. I freshened the 302 and M21, bagged them both and put them under the bench. I called Gail Trent at American Speed and told him I wanted a high revving smallblock to replace my MO engine. He came up with a 355 using a Crane off-road solid flat tappet cam that revs like no tomorrow.

I also installed a Tremec 5 speed and with the low 1st gear with the 3.73's getting the car moving is the best part. I have a 7K chip in the MSD and hit the limiter regularly. The 355 is dressed exactly like the 302, however, the difference between the 302 and the 355 is like night and day. The 355/Tremec combination is a lot more fun to drive. A reliable high revving engine is a blast and my next small block will be a 331.

I agree, but Jerrys 10.60s from his HHRA stock 302 dont look that bad to me when you compare them to a 427 small block running 10.0s.

Looks like about 6 car lengths to me at the stripe ;)

How much $$ do you think he has in that 302 Mark? Just curious because I know those Stock and Super Stock programs get REAL expensive.

10.60's out of a 302 is a sweet ride for sure, and I'm betting it takes a fair amount more effort and money than my big (these days more like medium) SBC combo. Not to mention drivability (I can still listen to my CD player driving down the freeway)

Please don't misunderstand my point here - I LOVE 302 cars, that's not the question. They did perform very well back in their hay-day. But looking at it from a $ per HP perspective cubic inches with aftermarket heads RULE.

Cubic inches + air flow = power . . . not bore = power or stroke = power. Look at where the serious drag race guys spend their money. It isn't developing a bigger bore shorter stroke engine, its in the heads (airflow).
Eric is right. HRM did a test a few years back of two big blocks that were identical except for bore and stroke. They were the same displacement, but one was big stroke, small bore and the other one was opposite. The two engines had IDENTICAL hp and torque curves! Stroke = torque is BS.

I will say, however, that bigger bores may open up flow possibilities in high horsepower engines with good heads. Like Eric points out, power is not in the crankshaft, it's in the heads. The HRM test did not bear this out because the heads they were using, which were the same on both engines, did not have intake valve shrouding issues in the smaller bore engine. Simply put, they could have put better heads with bigger valves on both engines and shown the advantage of big bore at high engine speeds.

Looks like about 6 car lengths to me at the stripe ;)

How much $$ do you think he has in that 302 Mark? Just curious because I know those Stock and Super Stock programs get REAL expensive.

10.60's out of a 302 is a sweet ride for sure, and I'm betting it takes a fair amount more effort and money than my big (these days more like medium) SBC combo. Not to mention drivability (I can still listen to my CD player driving down the freeway)

Please don't misunderstand my point here - I LOVE 302 cars, that's not the question. They did perform very well back in their hay-day. But looking at it from a $ per HP perspective cubic inches with aftermarket heads RULE.It is six cars, come on you know Id never recommend building a small block with less than 406 inches, unless it was a Z. Just having some fun on here:D but it is real cool driving around in a real 67 Z with gear, theres nothing like it! I dont think it would cost me that much to build a stocker 302 (NHRA D/S), but I think the clutch and trans would be where the money would be spent, and lots of it! Keep up the good work on your car:thumbsup:

13,000 RPM? You gotta be kidding! I find that hard to believe but I am no expert here. ;)
****,man i read a article on a 292 (283 .060 over bore) in a willys that launch at close to 9,500 and shifted at 10,500 now it was built to the hilt but a beast nonetheless.

This engine would probably run like an equally built 327 but with the following advantages:

The larger bore would both unshroud the valves and allow for larger valves.

Less stress on and parasitic loss in the bottom end.

However, I wouldn't build one. I would stay away from bearing spacers, and if going to an aftermarket crank there is no reason not to use one with 3.75" or longer stroke. In a Z/28, I can see the reasons to build a 302(That's what I did). Back then, that was about the largest screamer you could build with the head and cam technology that was in existence. But with today's technology, unless you are building a 302 for it's nostalgia, there isn't a real reason to ignore the possibility of a screamin' large cube small block which will deliver more of everything everywhere on the curve. You can squeeze more top end hp out of any particular head with a smaller motor but that will require insane gears and a real light car to make work.

So, if you have a 400 block, I'd build it as a 400, but bolt some real big aftermarket heads on there, longer rods, and a long duration, high lift, tight lash solid cam and you'd have something that runs like a 302 but with more torque and power everywhere.

HRM did a test a few years back of two big blocks that were identical except for bore and stroke. They were the same displacement, but one was big stroke, small bore and the other one was opposite. The two engines had IDENTICAL hp and torque curves! Stroke = torque is BS.

I don't know that I really buy that.
When comparing a 350 to a 383, where does the extra torque come from? Bore doesn't change - it's the leverage in the arm.
Build a 454, then build a 4.0" stroke, 4.60 bore engine. The extra surface area for the expanding gasses to work on is what gives extra torque in this situation.
Either way, you're building a bigger motor, whether by bigger bore or longer arm. The test that was done with the 500+/- engines did show a bit of difference but not much. The combos were not optimized, I don't know of anyone that would build a short stroke/big bore engine and run the same cam as a big stroker - did you ever see anyone wringing out a 350 like we're talking about doing with a 302?.

Build it as big and strong as you can afford or you'll get tired of getting your butt handed to you by those that do.

Torque moves the car. Rev the motor that high! Your asking for trouble. Build a motor that will give you 500ft lbs of torque, at 4000 rpm. Run 6500 rpm max. You will be very happy. The motor you are talking about, won't last. And you will get your but handed to you on the street. Why are big blocks badass! Torque! 406 cubic inch smallblock or better, will be next closest thing.

Eric is right. HRM did a test a few years back of two big blocks that were identical except for bore and stroke. They were the same displacement, but one was big stroke, small bore and the other one was opposite. The two engines had IDENTICAL hp and torque curves! Stroke = torque is BS.
i call bs on this article becuase everythng ive read even with the same components the engine will gain or lose hp/tq not stay at the exact same.plus we have alot of hotrod magizines.and IF you have to prove me wrong post a link to the article.